Porphyria is any of a group of rare, metabolic disease due to disordered hemoglobin synthesis. It typically runs in families and may cause episodic abdominal pain, skin changes, neuritis, and mental changes. Certain drugs can precipitate acute attacks. Porphyria may have been the cause of the "madness" of George III of England.
Porphyria is caused by the accumulation of substances called porphyrins. These are chemicals formed in the body during the manufacture of heme (a component of hemoglobin) – the oxygen-carrying pigment in red blood cells). A block of this process causes a buildup of porphyrins, which can act as a poison. Such blocks may result from various genetic enzyme deficiencies. Porphyria may also be due to poisoning.
Types and symptoms
These are six types of porphyria, each of which has different symptoms. Sufferers often have a rash or blistering brought on by sunlight, and may have abdominal pain and nervous symptoms due to the effects of certain drugs or alcohol.
Acute intermittent porphyria
This form of the condition usually appears in early adulthood, causing abdominal pain, and often limb cramps, muscle weakness, and psychiatric disturbances. The patient's urine turns red when it is left to stand. Barbiturate drugs, phenytoin, oral contraceptives, and certain other drugs will precipitate attacks.
This form of the condition has similar effects to acute intermittent porphyria, and may be caused by the same drugs. An additional symptom is blistering on skin that is exposed to sunlight.
The form of the condition also has similar effects to acute intermittent porphyria, and may cause additional skin symptoms.
In this form of porphyria, mild skin symptoms appear following exposure to sunlight.
Porphyria cutanea tarda
This form of the condition causes blistering of skin that is exposed to the sun, but no disturbances of the digestive or nervous systems. Wounds are slow to heal, and urine is sometimes pink or brown. Many cases are precipitated by liver disease.
Congenital erythropoietic porphyria
This is the rarest and most serious form of porphyria. It causes red discoloration of urine and teeth, excessive hair growth, severe skin blistering and ulceration, and hemolytic anemia. Death may occur in childhood.
Diagnosis and treatment
Diagnosis of this condition is made from the presence of abnormal levels of porphyrins in the urine and feces.
Treatment of porphyria is difficult. Avoiding sunlight and/or precipitating drugs is the most important measure. Acute intermittent porphyria, hereditary coproporphyria, and variegate porphyry may be helped by the administration of glucose or hemin (a substance that is chemically related to heme).
Cases of porphyria cutanea tarda may sometimes be helped by venesection (withdrawing blood from a vein).